Hi and welcome! Seedlings can be both really rewarding and equally heartbreaking. Through some fluke i've managed to happily grow a few dozen Phalaenopsis schillerianas, but out of 40 Cymbidiums i have about 10 still alive. Add to that about half of my Dends have died from one bottle but NONE have died from the other.
All i can suggest is wait until the last moment to deflask. I'm not sure if this is a good idea in general, but while they're happy and growing in the bottle they're HAPPY AND GROWING! So don't annoy them! You want them to be as big as they can be before you let them loose.
And number 2 tip is give them really high humidity and really really good air flow for quite a few months out of the flask. This is my setup, a fishtank with a fan inside on a timer. I wet the vermiculite on the bottom periodically to keep it humid. When i first started i used a propagating box which had high humidity but no air movement and as a consequence i lost heaps of orchids to mould. And if i put them out in the air, they dried up and shrivelled to a crisp. Humidity AND air movement is key.
Anyway good luck!
Some links i've collected are:
Deflasking
Easy Orchids - Deflasking Orchids
Deflasking
Deflasking
Bottle Babies
Deflask
Caring for Seedlings Removed from Flasks and A Method of Compotting in Sphagnum